Compositions and methods for prelithiating energy storage devices

ABSTRACT

An energy storage device can include a cathode, an anode, and a separator between the cathode and the anode. At least one of the electrodes can include an electrode film prepared by a dry process. The electrode film and/or the electrode can comprise a prelithiating material. Processes and apparatuses used for fabricating the electrode and/or electrode film are also described.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57. Thisapplication claims the benefit of U.S. Provisional App. No. 62/792,544,filed on Jan. 15, 2019, the entirety of which is hereby incorporated byreference.

BACKGROUND Field

The present invention relates to energy storage devices, particularly tocompositions of and methods for fabricating energy storage deviceelectrodes.

Description of the Related Art

Various types of energy storage devices can be used to power electronicdevices, including for example, capacitors, batteries, capacitor-batteryhybrids and/or fuel cells. An energy storage device, such as atraditional or solid-state lithium ion capacitor or battery, having anelectrode prepared using an improved electrode formulation and/orfabrication process can facilitate improved capacitor electricalperformance. A lithium ion capacitor or battery having an electrodeprepared using an improved electrode formulation and/or fabricationprocess may demonstrate improved cycling performance, reduced equivalentseries resistance (ESR) values, increased power density performanceand/or increased energy density performance. Improved electrodeformulations and/or fabrication processes may also facilitate lowercosts of energy storage device fabrication.

SUMMARY

For purposes of summarizing the disclosure and the advantages achievedover the prior art, certain objects and advantages of the disclosure aredescribed herein. Not all such objects or advantages may be achieved inany particular embodiment. Thus, for example, those skilled in the artwill recognize that the invention may be embodied or carried out in amanner that achieves or optimizes one advantage or group of advantagesas taught herein without necessarily achieving other objects oradvantages as may be taught or suggested herein.

In a first aspect, a dry electrode film of an energy storage device isprovided. The dry electrode film includes a dry active material. The dryelectrode film further includes a dry binder. The dry electrode furtherfilm includes a dry prelithiating material distributed throughout thedry active material and the dry binder. The dry electrode film isfree-standing.

In some embodiments of the dry electrode film, the dry prelithiatingmaterial is Li₂O₂. In some embodiments, the dry active material is a drycathode active material. In some embodiments, the dry cathode activematerial comprises sulfur or a material comprising sulfur.

In a second aspect, a method of fabricating a dry electrode film of anenergy storage device is provided. The method includes mixing a dryprelithiating material and a dry conductive carbon additive to form afirst dry mixture. The method further includes mixing the first drymixture with a dry active material to form a second dry mixture. Themethod further includes adding a dry fibrillizable binder to the seconddry mixture to form a dry electrode film mixture. The method furtherincludes fibrillizing the dry binder in the dry electrode film mixture.

In some embodiments of the method, the method further comprisescalendering the dry electrode film mixture to form a free-standing dryelectrode film. In some embodiments, mixing the first dry mixture withthe dry active material further comprises mixing a dry carbon materialand a dry conductive carbon material to form the second dry mixture. Insome embodiments, mixing the dry prelithiating material and the dryconductive carbon additive is performed so that the temperature of thefirst mixture is at most about 100° C. In some embodiments, mixing thedry prelithiating material and the dry conductive carbon additiveresults in electrical contact between primary particles of theprelithiating material and the conductive carbon additive. In someembodiments, mixing the dry prelithiating material and the dryconductive carbon additive is performed without excessive heating of thefirst dry mixture. In some embodiments, the ratio of the dryprelithiating material and the dry conductive carbon additive is about5:1 to about 5:3.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of the preferred embodiments having reference to theattached figures, the invention not being limited to any particularpreferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are described with reference to the drawings of certainembodiments, which are intended to illustrate certain embodiments andnot to limit the invention.

FIG. 1 is a schematic cross-sectional view of a prelithiated energystorage device, according to an embodiment.

FIG. 2 is a process flow diagram showing an example of a process forfabricating an electrode film from an electrode film mixture comprisinga prelithiating material.

FIG. 3A shows an SEM image of the lithium peroxide as received.

FIG. 3B shows an SEM image of the lithium peroxide mixed with the SuperPcarbon black at a 5 to 2 ratio.

FIG. 4 shows an image of a laminated electrode comprising lithiumperoxide submerged in water.

FIG. 5 compares the electrochemical profiles of an electrochemical cellcomprising 2% lithium peroxide compared to and control cell withoutlithium peroxide.

DETAILED DESCRIPTION

The present disclosure is related to electrode films including aprelithiating material, and methods of fabricating thereof, for use inan energy storage device. For example, a prelithiating material may beincorporated into the electrode film to compensate for the lithiumconsumed in the formation of a solid electrolyte interphase (SEI) layeron the electrode during initial cycling of a corresponding energystorage device. Reaction of the prelithiating material may also producea gas, which may beneficially increase the porosity of the electrode.

Definitions

As used herein, the terms “battery” and “capacitor” are to be giventheir ordinary and customary meanings to a person of ordinary skill inthe art. The terms “battery” and “capacitor” are nonexclusive of eachother. A capacitor or battery can refer to a single electrochemical cellthat may be operated alone, or operated as a component of a multi-cellsystem.

As provided herein, a “self-supporting” electrode film is an electrodefilm that incorporates binder matrix structures sufficient to supportthe film or layer and maintain its shape such that the electrode film orlayer can be free-standing. When incorporated in an energy storagedevice, a self-supporting electrode film or active layer is one thatincorporates such binder matrix structures. Generally, and depending onthe methods employed, such electrode films or active layers are strongenough to be employed in energy storage device fabrication processeswithout any outside supporting elements, such as a current collector,support webs or other structures, although supporting elements may beemployed to facilitate the energy storage device fabrication processes.For example, a “self-supporting” electrode film can have sufficientstrength to be rolled, handled, and unrolled within an electrodefabrication process without other supporting elements. A dry electrodefilm, such as a cathode electrode film or an anode electrode film, maybe self-supporting.

As provided herein, a “solvent-free” electrode film is an electrode filmthat contains no detectable processing solvents, processing solventresidues, or processing solvent impurities. A dry electrode film, suchas a cathode electrode film or an anode electrode film that ismanufactured with only dry components, may be solvent-free.

A “wet” electrode, “wet process” electrode, or slurry electrode, is anelectrode or comprises an electrode film prepared by at least one stepinvolving a slurry of active material(s), binder(s), and optionallyadditive(s), even if a subsequent drying step removes moisture from theelectrode or electrode film. Thus, a wet electrode or wet electrode filmwill include at least one or more processing solvents, processingsolvent residues, and/or processing solvent impurities.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements, and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements, and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements, and/or steps areincluded or are to be performed in any particular embodiment.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than 10% of, within less than 5% of, within less than 1% of, withinless than 0.1% of, and within less than 0.01% of the stated amount,depending on the desired function or desired result.

DESCRIPTION

Although certain embodiments and examples are described below, those ofskill in the art will appreciate that the invention extends beyond thespecifically disclosed embodiments and/or uses and obvious modificationsand equivalents thereof. Thus, it is intended that the scope of theinvention herein disclosed should not be limited by any particularembodiments described below.

In attempts to increase the energy density of lithium ionelectrochemical devices, high specific energy density anode materials,such as silicon, are being explored. During the first charge, lithiumfrom the cathode material is consumed during the formation process of asolid electrolyte interphase (SEI) layer, which acts as a protectivelayer around the anode. However, lithium ions consumed in this formationof the SEI layer are no longer available for cycling during normaloperation of the electrochemical devices, resulting in reducedperformance potential. Described below is an electrode film compositionand formation process that allows the introduction of a prelithiatingmaterial into the electrode film mixture used to form a prelithiatedelectrode film. Some embodiments avoid or reduce decomposing theprelithiating material due to exposure to solvents and hightemperatures. Furthermore, in some embodiments, such a prelithiatingmaterial may have the added benefit of producing a prelithiatedelectrode with increased porosity.

FIG. 1 shows a side cross-sectional schematic view of an example of aprelithiated energy storage device 100 with a prelithiated electrodefilm. The energy storage device 100 may be classified as, for example, acapacitor, a battery, a capacitor-battery hybrid, or a fuel cell. Insome embodiments, device 100 is a lithium ion battery.

The device has a first electrode 102, a second electrode 104, and aseparator 106 positioned between the first electrode 102 and secondelectrode 104. The first electrode 102 and the second electrode 104 areadjacent to respective opposing surfaces of the separator 106. Theenergy storage device 100 includes an electrolyte 118 to facilitateionic communication between the electrodes 102, 104 of the energystorage device 100. For example, the electrolyte 118 may be in contactwith the first electrode 102, the second electrode 104 and the separator106. The electrolyte 118, the first electrode 102, the second electrode104, and the separator 106 are housed within an energy storage devicehousing 120.

One or more of the first electrode 102, the second electrode 104, andthe separator 106, or constituent thereof, may comprise porous material.The pores within the porous material can provide containment for and/orincreased surface area for contact with an electrolyte 118 within thehousing 120. The energy storage device housing 120 may be sealed aroundthe first electrode 102, the second electrode 104 and the separator 106,and may be physically sealed from the surrounding environment.

In some embodiments, the first electrode 102 can be an anode (the“negative electrode”) and the second electrode 104 can be the cathode(the “positive electrode”). The separator 106 can be configured toelectrically insulate two electrodes adjacent to opposing sides of theseparator 106, such as the first electrode 102 and the second electrode104, while permitting ionic communication between the two adjacentelectrodes. The separator 106 can comprise a suitable porous,electrically insulating material. In some embodiments, the separator 106can comprise a polymeric material. For example, the separator 106 cancomprise a cellulosic material (e.g., paper), a polyethylene (PE)material, a polypropylene (PP) material, and/or a polyethylene andpolypropylene material.

Generally, the first electrode 102 and second electrode 104 eachcomprise a current collector and an electrode film. Electrodes 102 and104 comprise electrode films 112 and 114 with high electrode filmdensities and/or high electronic densities, respectively. Electrodes 102and 104 each have a single electrode film 112 and 114 as shown, butother combinations with two or more electrode films for each electrode102 and 104 are possible. Device 100 is shown with a single electrode102 and a single electrode 104, but other combinations are possible.Electrode films 112 and 114 can each have any suitable shape, size andthickness. For example, the electrode films can each have a thickness ofabout 30 microns (μm) to about 250 microns, for example, about, or atleast about 50 microns, about 100 microns, about 150 microns, about 200microns, about 250 microns, about 300 microns, about 400 microns, about500 microns, about 750 microns, about 1000 microns, about 2000 microns,or any range of values therebetween. Further electrode film thicknessesare described throughout the disclosure, for a single electrode film.The electrode films generally comprise one or more active materials, forexample, anode active materials or cathode active materials as providedherein. The electrode films 112 and/or 114 may be dry and/orself-supporting electrode films as provided herein, and havingadvantageous properties, such as thickness, increased electrode filmdensity, energy density, specific energy density, areal energy density,areal capacity or specific capacity, as provided herein. The firstelectrode film 112 and/or the second electrode film 114 may also includeone or more binders as provided herein. The electrode films 112 and/or114 may be prepared by a process as described herein. The electrodefilms 112 and/or 114 may be wet or self-supporting dry electrodes asdescribed herein.

As shown in FIG. 1, the first electrode 102 and the second electrode 104include a first current collector 108 in contact with first electrodefilm 112, and a second current collector 110 in contact with the secondelectrode film 114, respectively. The first current collector 108 andthe second current collector 110 facilitate electrical coupling betweeneach corresponding electrode film and an external electrical circuit(not shown). The first current collector 108 and/or the second currentcollector 110 comprise one or more electrically conductive materials,and can have any suitable shape and size selected to facilitate transferof electrical charge between the corresponding electrode and an externalcircuit. For example, a current collector can include a metallicmaterial, such as a material comprising aluminum, nickel, copper,rhenium, niobium, tantalum, and noble metals such as silver, gold,platinum, palladium, rhodium, osmium, iridium and alloys andcombinations of the foregoing. For example, the first current collector108 and/or the second current collector 110 can comprise, for example,an aluminum foil or a copper foil. The first current collector 108and/or the second current collector 110 can have a rectangular orsubstantially rectangular shape sized to provide transfer of electricalcharge between the corresponding electrode and an external circuit.

With continued reference to FIG. 1, the second electrode film 114 isprelithiated. However, it is to be understood that the first electrodefilm 112 may be prelithiated, or both electrode films 112 and 114 may beprelithiated. Electrode films 112 and/or 114 may be prelithiated asdescribed herein.

In some embodiments, the energy storage device 100 is charged with asuitable lithium-containing electrolyte 118. For example, device 100 caninclude a lithium salt, and a solvent, such as a non-aqueous or organicsolvent. Generally, the lithium salt includes an anion that is redoxstable. In some embodiments, the anion can be monovalent. In someembodiments, a lithium salt can be selected from hexafluorophosphate(LiPF₆), lithium tetrafluoroborate (LiBF₄), lithium perchlorate(LiClO₄), lithium bis(trifluoromethansulfonyl)imide (LiN(SO₂CF₃)₂),lithium trifluoromethansulfonate (LiSO₃CF₃), lithium bis(oxalate)borate(LiBOB) and combinations thereof. In some embodiments, the electrolytecan include a quaternary ammonium cation and an anion selected from thegroup consisting of hexafluorophosphate, tetrafluoroborate and iodide.In some embodiments, the salt concentration can be about 0.1 mol/L (M)to about 5 M, about 0.2 M to about 3 M, or about 0.3 M to about 2 M. Infurther embodiments, the salt concentration of the electrolyte can beabout 0.7 M to about 1 M. In certain embodiments, the salt concentrationof the electrolyte can be about 0.2 M, about 0.3 M, about 0.4 M, about0.5 M, about 0.6 M, about 0.7 M, about 0.8 M, about 0.9 M, about 1 M,about 1.1 M, about 1.2 M, or any range of values therebetween.

In some embodiments, an energy storage device electrolyte as providedherein can include a liquid solvent. A solvent as provided herein neednot dissolve every component, and need not completely dissolve anycomponent, of the electrolyte. In further embodiments, the solvent canbe an organic solvent. In some embodiments, a solvent can include one ormore functional groups selected from carbonates, ethers and/or esters.In some embodiments, the solvent can comprise a carbonate. In furtherembodiments, the carbonate can be selected from cyclic carbonates suchas, for example, ethylene carbonate (EC), propylene carbonate (PC),vinyl ethylene carbonate (VEC), vinylene carbonate (VC), fluoroethylenecarbonate (FEC), and combinations thereof, or acyclic carbonates suchas, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC),ethyl methyl carbonate (EMC), and combinations thereof. In certainembodiments, the electrolyte can comprise LiPF₆, and one or morecarbonates.

In some embodiments, the lithium ion battery is configured to operate atabout 2.5 to 4.5 V, or 3.0 to 4.2 V. In further embodiments, the lithiumion battery is configured to have a minimum operating voltage of about2.5 V to about 3 V, respectively. In still further embodiments, thelithium ion battery is configured to have a maximum operating voltage ofabout 4.1 V to about 4.4 V, respectively.

In some embodiments, a method for fabricating an energy storage deviceis provided. In further embodiments, the method comprises selecting ananode and a cathode. In some embodiments, selecting the anode comprisesselecting a dry self-supporting anode or a wet anode. In furtherembodiments, selecting the cathode comprises selecting a dryself-supporting cathode or a wet cathode. The step of selecting a dryanode may comprise selecting an active material processing method, andselecting a binder processing method.

In some embodiments, an electrode film as provided herein includes atleast one active material and at least one binder. The at least oneactive material can be any active material known in the art. The atleast one active material may be a material suitable for use in theanode or cathode of a battery. Anode active materials can comprise, forexample, an insertion material (such as carbon, graphite, and/orgraphene), an alloying/dealloying material (such as silicon, siliconoxide, tin, and/or tin oxide), a metal alloy or compound (such as Si—Al,and/or Si—Sn), and/or a conversion material (such as manganese oxide,molybdenum oxide, nickel oxide, and/or copper oxide). The anode activematerials can be used alone or mixed together to form multi-phasematerials (such as Si—C, Sn—C, SiOx-C, SnOx-C, Si—Sn, Si-SiOx, Sn-SnOx,Si-SiOx-C, Sn-SnOx-C, Si—Sn—C, SiOx-SnOx-C, Si-SiOx-Sn, orSn-SiOx-SnOx.).

The cathode active material, can comprise, for example, a metal oxide,metal sulfide, or a lithium metal oxide. The lithium metal oxide can be,for example, a lithium nickel manganese cobalt oxide (NMC), a lithiummanganese oxide (LMO), a lithium iron phosphate (LFP), a lithium cobaltoxide (LCO), a lithium titanate (LTO), and/or a lithium nickel cobaltaluminum oxide (NCA). In some embodiments, cathode active materials cancomprise, for example, a layered transition metal oxide (such as LiCoO₂(LCO), Li(NiMnCo)O₂ (NMC) and/or LiNi_(0.8)C_(0.15)Al_(0.05)O₂ (NCA)), aspinel manganese oxide (such as LiMn₂O₄ (LMO) and/orLiMn_(1.5)Ni_(0.5)O₄ (LMNO)) or an olivine (such as LiFePO₄). Thecathode active material can comprise sulfur or a material includingsulfur, such as lithium sulfide (Li₂S), or other sulfur-based materials,or a mixture thereof. In some embodiments, the cathode film comprises asulfur or a material including sulfur active material at a concentrationof at least 50 wt %. In some embodiments, the cathode film comprising asulfur or a material including sulfur active material has an arealcapacity of at least 6 mAh/cm². In some embodiments, the cathode filmcomprising a sulfur or a material including sulfur active material hasan electrode film density of 1 g/cm³. In some embodiments, the cathodefilm comprising a sulfur or a material including sulfur active materialfurther comprises a binder. In some embodiments, the binder of thecathode film comprising a sulfur or a material including sulfur activematerial is selected from polytetrafluoroethylene (PTFE), polyvinylidenefluoride (PVDF), polyethylene (PE), other thermoplastics, or anycombination thereof.

The electrode film can comprise the at least one active materialcombined with one or more carbon materials. The carbon materials may beselected from, for example, graphitic material, graphite,graphene-containing materials, hard carbon, soft carbon, carbonnanotubes, porous carbon, conductive carbon, or a combination thereof.Activated carbon can be implemented, for example, activated carbonderived from a steam process or an acid/etching process. In someembodiments, the graphitic material can be a surface treated material.In some embodiments, the porous carbon can comprise activated carbon. Insome embodiments, the porous carbon can comprise hierarchicallystructured carbon. In some embodiments, the porous carbon can includestructured carbon nanotubes, structured carbon nanowires and/orstructured carbon nanosheets. In some embodiments, the porous carbon caninclude graphene sheets. In some embodiments, the porous carbon can be asurface treated carbon. In some embodiments, these carbon materialsdescribed here can be a different material than the conductive carbonadditive and/or the conductive carbon material described in furtherdetail below with respect to the Examples 1 and 2 and the process shownin FIG. 2.

In some embodiments, a cathode electrode film of a lithium ion batteryor hybrid energy storage device can include about 70 weight % to about98 weight % of the at least one active material, including about 70weight % to about 92 weight %, or about 70 weight % to about 96 weight%. In some embodiments, a cathode electrode film can comprise about orup to about 70 weight %, about or up to about 90 weight %, about or upto about 92 weight %, about 94 weight %, about 95 weight %, about or upto about 96 weight % or about or up to about 98 weight % of the at leastone active material, or any range of values therebetween. In someembodiments, a cathode electrode film of a lithium ion battery or hybridenergy storage device can include about 40 weight % to about 60 weight %of the at least one active material. In some embodiments, the cathodeelectrode film can comprise up to about 10 weight % of the porous carbonmaterial, including up to about 5 weight %, or about 1 weight % to about5 weight %. In some embodiments, the cathode electrode film can compriseabout or up to about 10 weight %, about or up to about 5 weight %, aboutor up to about 1 weight % or about or up to about 0.5 weight % of theporous carbon material, or any range of values therebetween. In someembodiments, the cathode electrode film comprises up to about 5 weight%, including about 1 weight % to about 3 weight %, of the conductiveadditive. In some embodiments, the cathode electrode film comprisesabout or up to about 10 weight %, 5 weight %, about or up to about 3weight % or about or up to about 1 weight % of the conductive additive,or any range of values therebetween. In some embodiments, the cathodeelectrode film comprises up to about 20 weight % of the binder, forexample, about 1.5 weight % to 10 weight %, about 1.5 weight % to 5weight %, or about 1.5 weight % to 3 weight %. In some embodiments, thecathode electrode film comprises about 1.5 weight % to about 3 weight %binder. In some embodiments, the cathode electrode film comprises aboutor up to about 20 weight %, about or up to about 15 weight %, about orup to about 10 weight %, about or up to about 5 weight %, about or up toabout 3 weight %, about or up to about 1.5 weight % or about or up toabout 1 weight % of the binder, or any range of values therebetween.

In some embodiments, an anode electrode film may comprise at least oneactive material, a binder, and optionally a conductive additive and/or aconductive material. In some embodiments, the conductive additive maycomprise a conductive carbon additive, such as a carbon black. In someembodiments, the conductive material may comprise a conductive carbonmaterial, such as a carbon black. In some embodiments, the conductivecarbon additive is a different type and/or amount of material to theconductive carbon material. For example, in some embodiments, theconductive carbon additive and the conductive carbon material aredifferent carbon black materials. In some embodiments, the at least oneactive material of the anode may comprise synthetic graphite, naturalgraphite, hard carbon, soft carbon, graphene, mesoporous carbon,silicon, silicon oxides, tin, tin oxides, germanium, lithium titanate,mixtures, or composites of the aforementioned materials. In someembodiments, an anode electrode film can include about 80 weight % toabout 98 weight % of the at least one active material, including about80 weight % to about 98 weight %, or about 94 weight % to about 97weight %. In some embodiments, an anode electrode film can include about80 weight %, about 85 weight %, about 90 weight %, about 92 weight %,about 94 weight %, about 95 weight %, about 96 weight %, about 97 weight% or about 98 weight % or about 99 weight % of the at least one activematerial, or any range of values therebetween. In some embodiments, theanode electrode film comprises up to about 5 weight %, including about 1weight % to about 3 weight %, of the conductive additive. In someembodiments, the anode electrode film comprises about or up to about 5weight %, about or up to about 3 weight %, about or up to about 1 weight% or about or up to about 0.5 weight % of the conductive additive, orany range of values therebetween. In some embodiments, the anodeelectrode film comprises up to about 20 weight % of the binder,including about 1.5 weight % to 10 weight %, about 1.5 weight % to 5weight %, or about 3 weight % to 5 weight %. In some embodiments, theanode electrode film comprises about 4 weight % binder. In someembodiments, the anode electrode film comprises about or up to about 20weight %, about or up to about 15 weight %, about or up to about 10weight %, about or up to about 5 weight %, about or up to about 3 weight%, about or up to about 1.5 weight % or about or up to about 1 weight %of the binder, or any range of values therebetween. In some embodiments,the anode film may not include a conductive additive.

Some embodiments include an electrode film, such as of an anode and/or acathode, having one or more active layers comprising a polymeric bindermaterial. The binder can include polytetrafluoroethylene (PTFE), apolyolefin, polyalkylenes, polyethers, styrene-butadiene, co-polymers ofpolysiloxanes and polysiloxane, branched polyethers, polyvinylethers,co-polymers thereof, and/or admixtures thereof. The binder can include acellulose, for example, carboxymethylcellulose (CMC). In someembodiments, the polyolefin can include polyethylene (PE), polypropylene(PP), polyvinylidene fluoride (PVDF), co-polymers thereof, and/ormixtures thereof. For example, the binder can include polyvinylenechloride, poly(phenylene oxide) (PPO), polyethylene-block-poly(ethyleneglycol), poly(ethylene oxide) (PEO), poly(phenylene oxide) (PPO),polyethylene-block-poly(ethylene glycol), polydimethylsiloxane (PDMS),polydimethylsiloxane-coalkylmethylsiloxane, co-polymers thereof, and/oradmixtures thereof. In some embodiments, the binder may be athermoplastic. In some embodiments, the binder comprises a fibrillizablepolymer. In certain embodiments, the binder comprises, consistsessentially, or consists of a single fibrillizable binder, such as PTFE.

In some embodiments, the binder may comprise PTFE and optionally one ormore additional binder components. In some embodiments, the binder maycomprise one or more polyolefins and/or co-polymers thereof, and PTFE.In some embodiments, the binder may comprise a PTFE and one or more of acellulose, a polyolefin, a polyether, a precursor of polyether, apolysiloxane, co-polymers thereof, and/or admixtures thereof. Anadmixture of polymers may comprise interpenetrating networks of theaforementioned polymers or co-polymers.

The binder may include various suitable ratios of the polymericcomponents. For example, PTFE can be up to about 98 weight % of thebinder, for example, from about 20 weight % to about 95 weight %, about20 weight % to about 90 weight %, including about 20 weight % to about80 weight %, about 30 weight % to about 70 weight %, about 30 weight %to about 50 weight %, or about 50 weight % to about 90 weight %. In someembodiments, PTFE can be about or up to about 99 weight %, about or upto about 98 weight %, about or up to about 95 weight %, about or up toabout 90 weight %, about or up to about 80 weight %, about or up toabout 70 weight %, about or up to about 60 weight %, about or up toabout 50 weight %, about or up to about 40 weight %, about or up toabout 30 weight % or about or up to about 20 weight % of the binder, orany range of values therebetween.

In some embodiments, the electrode film mixture may include binderparticles having selected sizes. In some embodiments, the binderparticles may be about 50 nm, about 100 nm, about 150 nm, about 200 nm,about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm,about 500 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, about 5μm, about 10 μm, about 50 μm, about 100 μm, or any range of valuestherebetween.

As used herein, a dry electrode fabrication process can refer to aprocess in which no or substantially no solvents are used to form a dryelectrode film. For example, components of the active layer or electrodefilm, including carbon materials and binders, may comprise, consist of,or consist essentially of dry particles. The dry particles for formingthe active layer or electrode film may be combined to provide a dryparticle active layer mixture. In some embodiments, the active layer orelectrode film may be formed from the dry particle active layer mixturesuch that weight percentages of the components of the active layer orelectrode film and weight percentages of the components of the dryparticles active layer mixture are substantially the same. In someembodiments, the active layer or electrode film formed from the dryparticle active layer mixture using the dry fabrication process may befree from, or substantially free from, any processing additives such assolvents and solvent residues resulting therefrom. In some embodiments,the resulting active layer or electrode films are self-supporting filmsformed using the dry process from the dry particle mixture. In someembodiments, the resulting active layer or electrode films arefree-standing films formed using the dry process from the dry particlemixture. A process for forming an active layer or electrode film caninclude fibrillizing the fibrillizable binder component(s) such that thefilm comprises fibrillized binder. In further embodiments, afree-standing active layer or electrode film may be formed in theabsence of a current collector. In still further embodiments, an activelayer or electrode film may comprise a fibrillized polymer matrix suchthat the film is self-supporting. It is thought that a matrix, lattice,or web of fibrils can be formed to provide mechanical structure to theelectrode film.

In some embodiments, an energy storage device electrode film, whereinthe electrode film is dry and/or self-supporting film, may provide ahigh electrode material loading, or a high active material loading(which may be expressed as mass of electrode film per unit area ofelectrode film or current collector) of about 12 mg/cm², about 13mg/cm², about 14 mg/cm², about 15 mg/cm², about 16 mg/cm², about 17mg/cm², about 18 mg/cm², about 19 mg/cm², about 20 mg/cm², about 21mg/cm², about 22 mg/cm², about 23 mg/cm², about 24 mg/cm², about 25mg/cm², about 26 mg/cm², about 27 mg/cm², about 28 mg/cm², about 29mg/cm², about 30 mg/cm², about 40 mg/cm², about 50 mg/cm², about 60mg/cm², about 70 mg/cm², about 80 mg/cm², about 90 mg/cm² or about 100mg/cm², or any range of values therebetween. In some embodiments, anenergy storage device electrode film, wherein the electrode film is dryand/or self-supporting film, may provide a high electrode materialloading, or a high active material loading (which may be expressed asmass of electrode film per unit area of electrode film or currentcollector) of at least about 12 mg/cm², at least about 13 mg/cm², atleast about 14 mg/cm², at least about 15 mg/cm², at least about 16mg/cm², at least about 17 mg/cm², at least about 18 mg/cm², at leastabout 19 mg/cm², at least about 20 mg/cm², at least about 21 mg/cm², atleast about 22 mg/cm², at least about 23 mg/cm², at least about 24mg/cm², at least about 25 mg/cm², at least about 26 mg/cm², at leastabout 27 mg/cm², at least about 28 mg/cm², at least about 29 mg/cm², atleast about 30 mg/cm², at least about 40 mg/cm², at least about 50mg/cm², at least about 60 mg/cm², at least about 70 mg/cm², at leastabout 80 mg/cm², at least about 90 mg/cm² or at least about 100 mg/cm²,or any range of values therebetween.

An electrode film may have a selected thickness suitable for certainapplications. The thickness of an electrode film as provided herein maybe greater than that of an electrode film prepared by conventionalprocesses. In some embodiments, the electrode film can have a thicknessof about, or greater than about, 110 microns, about 115 microns, about120 microns, about 130 microns, about 135 microns, about 150 microns,about 155 microns, about 160 microns, about 170 microns, about 200microns, about 250 microns, about 260 microns, about 265 microns, about270 microns, about 280 microns, about 290 microns, about 300 microns,about 350 microns, about 400 microns, about 450 microns, about 500microns, about 750 microns, about 1 mm, or about 2 mm, or any range ofvalues therebetween. An electrode film thickness can be selected tocorrespond to a desired areal capacity, specific capacity, areal energydensity, energy density, or specific energy density.

In some embodiments, the electrode film porosity of an electrode film asprovided herein may be greater than that of an electrode film preparedby conventional processes. In some embodiments, the electrode filmporosity of an electrode film as provided herein may be less than thatof an electrode film prepared by conventional processes. In someembodiments, the electrode film can have an electrode film porosity(which may be expressed as the percentage of volume of electrode filmoccupied by pores) of about 10%, about 12%, about 14%, about 16%, about18% or about 20%, or any range of values therebetween. In someembodiments, the electrode film can have an electrode film porosity(which may be expressed as the percentage of volume of electrode filmoccupied by pores) of at least about 10%, at least about 12%, at leastabout 14%, at least about 16%, at least about 18% or at least about 20%,or any range of values therebetween. In some embodiments, the electrodefilm can have an electrode film porosity (which may be expressed as thepercentage of volume of electrode film occupied by pores) of at mostabout 10%, at most about 12%, at most about 14%, at most about 16%, atmost about 18% or at most about 20%, or any range of valuestherebetween.

In some embodiments, the electrode film density of an electrode film asprovided herein may be less than that of an electrode film prepared byconventional processes. In some embodiments, the electrode film densityof an electrode film as provided herein may be greater than that of anelectrode film prepared by conventional processes. In some embodiments,the electrode film can have an electrode film density of about 0.8g/cm³, 1.0 g/cm³, 1.4 g/cm³, about 1.5 g/cm³, about 1.6 g/cm³, about 1.7g/cm³, about 1.8 g/cm³, about 1.9 g/cm³, about 2.0 g/cm³, about 2.5g/cm³, about 3.0 g/cm³, about 3.3 g/cm³, about 3.4 g/cm³, about 3.5g/cm³, about 3.6 g/cm³, about 3.7 g/cm³ or about 3.8 g/cm³, or any rangeof values therebetween. In some embodiments, the electrode film can havean electrode film density of at most about 0.8 g/cm³, 1.0 g/cm³, 1.4g/cm³, at most about 1.5 g/cm³, at most about 1.6 g/cm³, at most about1.7 g/cm³, at most about 1.8 g/cm³, at most about 1.9 g/cm³ or at mostabout 2.0 g/cm³, or any range of values therebetween. In someembodiments, the electrode film can have density of at least about 0.8g/cm³, 1.0 g/cm³, 1.4 g/cm³, at least about 1.5 g/cm³, at least about1.6 g/cm³, at least about 1.7 g/cm³, at least about 1.8 g/cm³, at leastabout 1.9 g/cm³, at least about 2.0 g/cm³, at least about 2.5 g/cm³, atleast about 3.0 g/cm³, at least about 3.3 g/cm³, at least about 3.4g/cm³ or at least about 3.5 g/cm³, or any range of values therebetween.

In some embodiments, an energy storage device electrode film, whereinthe electrode film is dry and/or self-supporting film, may provide arealcapacity (which may be expressed as capacity per unit area of electrodefilm or current collector) of about, or at least about 3.5 mAh/cm²,about 3.8 mAh/cm², about 4 mAh/cm², about 4.3 mAh/cm², about 4.5mAh/cm², about 4.8 mAh/cm², about 5 mAh/cm², about 5.5 mAh/cm², about 6mAh/cm², about 6.5 mAh/cm², about 6.6 mAh/cm², about 7 mAh/cm², about7.5 mAh/cm², about 8 mAh/cm² or about 10 mAh/cm², or any range of valuestherebetween. In further embodiments, an energy storage device electrodefilm, wherein the electrode film is dry and/or self-supporting film, mayprovide areal capacity (which may be expressed as capacity per unit areaof electrode film or current collector) of at least about 8 mAh/cm², forexample, about 8 mAh/cm², about 10 mAh/cm², about 12 mAh/cm², about 14mAh/cm², about 16 mAh/cm², about 18 mAh/cm², about 20 mAh/cm², or anyrange of values therebetween. In some embodiments, the areal capacity ischarging capacity. In further embodiments, the areal capacity isdischarging capacity.

In some embodiments, a dry and/or self-supporting graphite battery anodeelectrode film may provide areal capacity of about 3.5 mAh/cm², about 4mAh/cm², about 4.5 mAh/cm², about 5 mAh/cm², about 5.5 mAh/cm², about 6mAh/cm², about 6.5 mAh/cm², about 7 mAh/cm², about 7.5 mAh/cm², about 8mAh/cm², about 8.5 mAh/cm², about 9 mAh/cm², about 10 mAh/cm², or anyrange of values therebetween. In some embodiments, the areal capacity ischarging capacity. In further embodiments, the areal capacity isdischarging capacity.

In some embodiments, an energy storage device electrode film, whereinthe electrode film is dry and/or self-supporting film, may provide aspecific capacity (which may be expressed as capacity per mass ofelectrode film or current collector) of about 150 mAh/g, about 160mAh/g, about 170 mAh/g, about 175 mAh/g, about 176 mAh/g, about 177mAh/g, about 179 mAh/g, about 180 mAh/g, about 185 mAh/g, about 190mAh/g, about 196 mAh/g, about 200 mAh/g, about 250 mAh/g, about 300mAh/g, about 350 mAh/g, about 354 mAh/g or about 400 mAh/g, or any rangeof values therebetween. In further embodiments, an energy storage deviceelectrode film, wherein the electrode film is dry and/or self-supportingfilm, may provide specific capacity (which may be expressed as capacityper mass of electrode film or current collector) of at least about 175mAh/g or at least about 250 mAh/g, or any range of values therebetween.In some embodiments, the specific capacity is charging capacity. Infurther embodiments, the specific capacity is discharging capacity. Insome embodiments, the electrode may be an anode and/or a cathode. Insome embodiment, the specific capacity may be a first charge and/ordischarge capacity. In further embodiments, the specific capacity may bea charge and/or discharge capacity measured after the first chargeand/or discharge.

In some embodiments, a self-supporting dry electrode film describedherein may advantageously exhibit improved performance relative to atypical electrode film. The performance may be, for example, tensilestrength, elasticity (extension), bendability, coulombic efficiency,capacity, or conductivity. In some embodiments, an energy storage deviceelectrode film, wherein the electrode film is dry and/or self-supportingfilm, may provide a coulombic efficiency (which may be expressed as apercent of the discharge capacity divided by the charge capacity) ofabout, or at least about, 85%, 86%, 87%, about 88%, about 89%, about90%, about 91%, about 92%, about 93%, about 94% or about 95%, or anyrange of values therebetween for example such as 90.1%, 90.5% and 91.9%,or any range of values therebetween.

In some embodiments, an energy storage device electrode film orelectrode, wherein the electrode film is or the electrode comprises adry and/or self-supporting film, may provide a charge capacity retentionpercentage (which may be expressed by the discharge capacity at a givenrate divided by the discharge capacity measured at C/10) of about or atleast about 10%, about or at least about 20%, about or at least about30%, about or at least about 40%, about or at least about 50%, about orat least about 60%, about or at least about 70%, about or at least about80%, about or at least about 90%, about or at least about 98%, about orat least about 99%, about or at least about 99.9% or about or at leastabout 100%, or any range of values therebetween. In some embodiments,the discharge rate of the charge capacity retention percentage is aboutor is at least about C/10, C/5, C/3, C/2, 1C, 1.5C or 2C, or any valuetherebetween.

In some embodiments, an energy storage device electrode film orelectrode, wherein the electrode film is or the electrode comprises adry and/or self-supporting film, may provide a charge capacityproduction percentage (which may be expressed by the charge capacitymeasured at a given constant current rate divided by the dischargecapacity measured at C/10) of about or at least about 10%, about or atleast about 20%, about or at least about, 30%, about or at least about,40%, about or at least about 50% about or at least about 60%, about orat least about 70%, about or at least about 80%, about or at least about90%, about or at least about 98%, about or at least about 99%, about orat least about 99.9% or about or at least about 100%, or any range ofvalues therebetween. In some embodiments, the charge rate of the chargecapacity production percentage is or is at least C/10, C/5, C/3, C/2,1C, 1.5C or 2C, or any value therebetween.

In some embodiments, an energy storage device electrode film, whereinthe electrode film is dry and/or self-supporting film, may provide aspecific energy density or gravimetric energy density (which may beexpressed as energy per mass of electrode film) of about 200 Wh/kg,about 210 Wh/kg, about 220 Wh/kg, about 230 Wh/kg, about 240 Wh/kg,about 250 Wh/kg, about 260 Wh/kg, about 270 Wh/kg, about 280 Wh/kg,about 290 Wh/kg, about 300 Wh/kg, about 400 Wh/kg, about 500 Wh/kg,about 600 Wh/kg, about 650 Wh/kg, about 700 Wh/kg, about 750 Wh/kg,about 800 Wh/kg, about 825 Wh/kg, about 850 Wh/kg or about 900 Wh/kg, orany range of values therebetween.

In some embodiments, an energy storage device electrode film, whereinthe electrode film is dry and/or self-supporting film, may provide anenergy density or volumetric energy density (which may be expressed asenergy per unit volume of the final or in situ electrode film) of about550 Wh/L, about 600 Wh/L, about 630 Wh/L, about 650 Wh/L, about 680Wh/L, about 700 Wh/L, about 750 Wh/L, about 850 Wh/L, about 950 Wh/L,about 1100 Wh/L, about 1400 Wh/L, about 1425 Wh/L, about 1450 Wh/L,about 1475 Wh/L, about 1500 Wh/L, about 1525 Wh/L or about 1550 Wh/L, orany range of values therebetween.

In some embodiments, a self-supporting dry battery cathode may exhibitreduced ohmic resistance and/or improved voltage polarizationcharacteristics compared to a wet battery cathode. In furtherembodiments, a lithium ion battery incorporating a self-supporting drycathode may advantageously exhibit reduced ohmic resistance and/orimproved voltage polarization characteristics compared to a lithium ionbattery having a wet cathode and a wet anode. In still furtherembodiments, a lithium ion battery incorporating a self-supporting drycathode may demonstrate improved energy density and/or specific energydensity, as compared to a lithium ion battery including a wet cathode.

In some embodiments, a self-supporting dry battery electrode after agingmay exhibit reduced ohmic resistance, improved voltage polarizationcharacteristics and/or improved capacity compared to an aged wet batteryelectrode. In some embodiments, the dry battery electrode after agingexhibits a reduction of ohmic resistance that is about 5 fold, about 10fold, about 15 fold or about 20 fold less than the reduction of ohmicresistance in a similarly aged wet battery electrode, or any range ofvalues therebetween. In some embodiments, the dry battery electrodeafter aging exhibits reduction of voltage of about 1.5 times, about 2times, about 3 times or about 5 times less than the reduction of voltagein a similarly aged wet battery electrode, or any range of valuestherebetween. In some embodiments, the dry battery electrode after agingexhibits reduction of capacity of about 1.5 times, about 2 times, about3 times or about 5 times less than the reduction of capacity in asimilarly aged wet battery electrode, or any range of valuestherebetween.

Prelithiation:

Prelithiation of an electrode may enable compensation of lithiumconsumed during initial cycling of the electrochemical device, which areno longer available for subsequent cycling. A sacrificial prelithiatingmaterial may be incorporated into the electrode in order to compensatefor the lithium consumed, for example, in the formation of a solidelectrolyte interphase (SEI) layer on the anode during initial cycling.

A prelithiating material as defined herein is a material comprising alithium that is oxidized when the electrochemical device is cycled toform free lithium ions and a byproduct. The lithium ions are then ableto be solvated by the electrolyte of the device. As such, theprelithiating material acts as a source of lithium from within anelectrode film, and compensates for the lithium ions consumed during thefirst charge process of an electrochemical device. In some embodiments,the prelithiating material is a strong reducing agent. In someembodiments the prelithiating material is a lithium oxide. In someembodiments, the prelithiating material is lithia (Li₂O), lithiumperoxide (Li₂O₂), Li₂S, Li₃N, LiN₃, LiF, LisFeO₄, Li₂NiO₂, Li₆CO₄,Li₂MoO₃, or mixtures thereof. In some embodiments, the prelithiatingmaterial is Li₂O₂. It will be understood that the prelithiating materialdoes not include elemental lithium metal, which is lithium metal havingan oxidation state of zero.

Reaction of the prelithiating material may also produce a beneficialbyproduct in addition to the lithiating an electrode. In someembodiments, the by-product may be a gas. For example, decomposition oflithium peroxide produces oxygen gas. The production of a gas from theprelithiating material within the electrode may beneficially increasethe porosity of the electrode.

In some embodiments, an electrode film mixture may comprise theprelithiating material in, or in about, 0.5 wt %, about 1 wt %, about1.5 wt %, about 2 wt %, about 3 wt %, about 4 wt %, about 5 wt %, about6 wt %, about 7 wt %, about 8 wt %, about 9 wt % or about 10 wt %, orany range of values therebetween.

FIG. 2 is a process flow diagram showing an example of a process 200 forfabricating an electrode film comprising a prelithiating material,according to some embodiments. In block 202, a first mixture comprisinga prelithiating material and a conductive carbon additive is formedthrough a mixing step. In some embodiments, the prelithiating materialis lithium peroxide. In some embodiments, the conductive carbon additiveis carbon black, as described herein. In some embodiments, the mixingshown in block 202 is performed without excessive heating of the firstmixture. In some embodiments, the mixing shown in block 202 is performedso that the temperature of the first mixture is at most or at most about200° C., 150° C., 140° C., 130° C., 120° C., 110° C., 100° C., 90° C.,80° C., 70° C., 60° C. or 50° C., or any range of values therebetween.In some embodiments, the mixing shown in block 202 is performed so thatthe temperature of the first mixture is below or below about 200° C.,150° C., 140° C., 130° C., 120° C., 110° C., 100° C., 90° C., 80° C.,70° C., 60° C. or 50° C., or any range of values therebetween. In someembodiments, the mixing shown in block 202 is performed by blending. Insome embodiments, the weight ratio of the prelithiating material to theconductive carbon additive is about 10:1, about 5:1, about 5:2, about5:3, about 5:4 or about 1:1, or any range of values therebetween. Insome embodiments, the prelithiating material and conductive carbonadditive are intimately mixed so as to evenly distribute the componentsthroughout the first mixture. In some embodiments, the prelithiatingmaterial and conductive carbon additive are mixed so as to result inelectrical contact between primary particles of the prelithiatingmaterial and conductive carbon additive.

In block 208, the first mixture of block 202 is mixed with an activematerial, a carbon material and a conductive carbon material to form asecond mixture. In some embodiments, the active material, carbonmaterial and conductive carbon material are first mixed to form anadditional mixture, prior to being mixed with the first mixture of block202. In some embodiments, the conductive carbon material is carbonblack, as described herein. In some embodiments, the carbon materialand/or the conductive carbon material are not utilized in block 208 toform the second mixture. In some embodiments, the mixing shown in block208 is performed by blending. In some embodiments, the mixing shown inblock 208 is performed so that the temperature of the first mixture isat most or at most about 200° C., 150° C., 140° C., 130° C., 120° C.,110° C., 100° C., 90° C., 80° C., 70° C., 60° C. or 50° C., or any rangeof values therebetween. In some embodiments, the mixing shown in block208 is performed so that the temperature of the first mixture is belowor below about 200° C., 150° C., 140° C., 130° C., 120° C., 110° C.,100° C., 90° C., 80° C., 70° C., 60° C. or 50° C., or any range ofvalues therebetween. In some embodiments, the first mixture, activematerial, carbon material and a conductive carbon material areintimately mixed so as to evenly distribute the components throughoutthe second mixture. In some embodiments, the mixing process of block 208is utilized to break or modify particles of the active material. In someembodiments, modified particles of the active material act to catalyzethe reaction of the prelithiating material during initial cycling of theelectrochemical device.

In some embodiments, the mixing steps of blocks 202 and 208 may utilizea continuous mixing process. In such embodiments, the duration ofblending and/or milling can be inversely related to the feed rate.Generally, the feed rate is dependent on the milling machinery, and canbe adjusted based on the machine operating parameters in view ofguidance provided herein. In further embodiments, equipment with largerchannels can be used to increase the duration of blending and/ormilling. When a batch blending and/or milling process is used, theduration can be increased simply by blending and/or milling for a longertime and/or at higher RPMs.

In block 210, an electrode film mixture is formed by adding afibrillizable binder to the second mixture of block 208. In someembodiments, the fibrillizable binder and the second mixture can beintimately mixed so as to evenly distribute the components throughoutthe electrode film mixture. In block 212, the fibrillizable binder inelectrode film mixture can be fibrillized to form fibrils from thebinder material. The fibrillization process can be performed withreduced speed and/or increased process pressure. The reduced speedand/or increased process pressure may facilitate increased formation offibrils such that a reduced quantity of binder material can be used toform the electrode film having the desired resistance to a tensile,shear, compressive, and/or twisting stress. As described herein, in someembodiments, the fibrillization process can be a mechanical shearingprocess, for example, comprising a blending and/or a milling process,and in some embodiments, a high shear process such as jet milling. Insome embodiments, the speed with which particles of the electrode filmmixture are cycled through the blender and/or mill may be reduced duringthe fibrillization process. In some embodiments, the process pressurewithin the blender and/or mill during the fibrillization process may beincreased. In some embodiments, the adding step of block 210 andfibrillization step of block 212 may be one or substantially onecontinuous step. The reduced speed and/or increased process pressure canallow an electrode film with a sufficiently great strength to bemanufactured, for example such as a free-standing electrode film, eitherthrough a single, higher pressure calendering process (in a singlestep), or through multiple calendering steps, for example, where thefilm is unwound, and subsequently re-calendered, one or more times afteran initial calendering step.

In block 214, the electrode film mixture can be calendered in a calenderapparatus to form a free-standing fibrillized electrode film. A calenderapparatus is well known in the art, and generally includes a pair ofcalender rolls (possessing either mechanically fixed gap or a hydraulicor pneumatic pressure fixed gap) between which raw material, such as anelectrode film mixture is fed, to form an electrode film. In someembodiments, an electrode film can be formed in a first calenderingstep, without additional calendering steps, to form a film at a desiredminimum thickness, as described further herein. In some embodiments, thecalendered mixture forms a free-standing dry particle film free orsubstantially free from any liquids, solvents, and resulting residuetherefrom. In some embodiments, the electrode film is an anode electrodefilm. In some embodiments, the electrode film is a cathode electrodefilm.

In some embodiments, the process 200 for fabricating an electrode filmis a dry process, where no liquids or solvents are used and the listedraw materials are dry (e.g. one or more are dry powders) such that theresulting electrode film is free or substantially free of any liquids,solvents, and resulting residues. In other wet electrode film processes,prelithiating materials may react with solvents, for example PVDF andN-Methyl-2-pyrrolidone (NMP), which may produce side products that couldnegatively impact the performance of the energy storage device. As such,a dry electrode process may offer a unique method to incorporateprelithiating material into an electrode film without exposure tosolvents. Furthermore, polytetrafluoroethylene (PTFE) may beadvantageously utilized as it is resistant to some acceptableprelithiating materials, for example lithium peroxide.

In specific examples below, high energy density, high specific energydensity, high thickness and/or high electrode film density batteryelectrodes were fabricated.

EXAMPLES Example 1

Example 1 describes an electrode film formed according to the processdescribed in FIG. 2. Lithium peroxide is mixed with SuperP carbon blackat a 5 to 2 ratio in a Waring blender for 10 minutes on low setting inan Argon glovebox. FIG. 3A shows an SEM image of the lithium peroxide,which demonstrates submicron primary particles. FIG. 3B shows an SEMimage of the lithium peroxide mixed with the SuperP carbon black at a 5to 2 ratio, which demonstrates intimate mixing and uniform distributionof both components. As described with reference to FIG. 2, this firstdry mixture was mixed to ensure dispersion of lithium peroxide with theelectrical conductive carbon black, wherein the lithium peroxide andSuperP were blended with intermittent 30 second pulses at 3000 rpm with30 seconds of cooling in between. The aforementioned blending limitedthe temperature of the lithium peroxide and SuperP mixture to belowabout 100° C. in order to avoid excessive heating of the mixture duringblending.

A pre-densified mixture of cathode active material NMC-622, activatedcarbon, and ketjen black was formed, to which the lithiumperoxide/SuperP mixture was then added to and blended with in the Argonglovebox on low setting for 5 minutes. Blending was performed in part tobreaks up a small fraction of the cathode active material secondaryparticles, so as to cause the smaller primary particles to act ascatalysts for the oxygen evolution reaction of lithium peroxide duringthe initial cycling of an electrochemical device. Finally, a PTFE binderwas added to the mixture, and the binder was fibrillized to form anelectrode film mixture.

Calendaring of the electrode film mixture was performed in a dry room tominimize powder exposure to moisture to form a free-standing electrodefilm. The free-standing electrode film is then further calendared to thedesired loading and laminated onto an aluminum foil with an adhesivecoating to form a cathode electrode.

FIG. 4 shows an image of such a laminated electrode submerged in water.In FIG. 4 the evolution of oxygen gas bubbles can be seen on the surfaceof the laminated electrode, which indicates that the lithium peroxidepresent in the electrode is still active and has not decomposed. Thereaction of lithium peroxide and water follows the chemical equation:

2Li₂O₂+2H₂O→4LiOH+O₂

Example 2

FIG. 5 shows the electrochemical profiles of a 2% lithium peroxide cellproduced in Example 1, and control cell without lithium peroxide. Theelectrochemical cycling of lithium peroxide containing lithium ioncathode electrode shows increased initial charge capacity due toelectrochemical release of oxygen from lithium peroxide and an increasein charge capacity of approximately 10 mAh/g is observed when 2% lithiumperoxide is added, which accounts to about 45% of the theoretical 22mAh/g if all lithium peroxide is utilized. This extra charge capacitymay be used to compensate for irreversible capacity of the anode duringformation cycles.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the systems and methodsdescribed herein may be made without departing from the spirit of thedisclosure. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the disclosure.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example described inthis section or elsewhere in this specification unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The protection is notrestricted to the details of any foregoing embodiments. The protectionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

Furthermore, certain features that are described in this disclosure inthe context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations, one or more features from a claimedcombination can, in some cases, be excised from the combination, and thecombination may be claimed as a subcombination or variation of asubcombination.

Moreover, while operations may be depicted in the drawings or describedin the specification in a particular order, such operations need not beperformed in the particular order shown or in sequential order, or thatall operations be performed, to achieve desirable results. Otheroperations that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the described operations. Further, the operations may berearranged or reordered in other implementations. Those skilled in theart will appreciate that in some embodiments, the actual steps taken inthe processes illustrated and/or disclosed may differ from those shownin the figures. Depending on the embodiment, certain of the stepsdescribed above may be removed, others may be added. Furthermore, thefeatures and attributes of the specific embodiments disclosed above maybe combined in different ways to form additional embodiments, all ofwhich fall within the scope of the present disclosure. Also, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the describedcomponents and systems can generally be integrated together in a singleproduct or packaged into multiple products. For example, any of thecomponents for an energy storage system described herein can be providedseparately, or integrated together (e.g., packaged together, or attachedtogether) to form an energy storage system.

For purposes of this disclosure, certain aspects, advantages, and novelfeatures are described herein. Not necessarily all such advantages maybe achieved in accordance with any particular embodiment. Thus, forexample, those skilled in the art will recognize that the disclosure maybe embodied or carried out in a manner that achieves one advantage or agroup of advantages as taught herein without necessarily achieving otheradvantages as may be taught or suggested herein.

The headings provided herein, if any, are for convenience only and donot necessarily affect the scope or meaning of the devices and methodsdisclosed herein.

The scope of the present disclosure is not intended to be limited by thespecific disclosures of preferred embodiments in this section orelsewhere in this specification, and may be defined by claims aspresented in this section or elsewhere in this specification or aspresented in the future. The language of the claims is to be interpretedbroadly based on the language employed in the claims and not limited tothe examples described in the present specification or during theprosecution of the application, which examples are to be construed asnon-exclusive.

What is claimed is:
 1. A dry electrode film of an energy storage device,comprising: a dry active material; a dry binder; and a dry prelithiatingmaterial evenly distributed throughout the dry active material and thedry binder, wherein the dry electrode film is free-standing.
 2. The dryelectrode film of claim 1, wherein the dry prelithiating material isselected from the group consisting of Li₂O, Li₂O₂, Li₂S, Li₃N, LiN₃,LiF, Li₅FeO₄, Li₂NiO₂, Li₆CO₄, and Li₂MoO₃, or combinations thereof. 3.The dry electrode film of claim 1, wherein the dry prelithiatingmaterial is Li₂O₂.
 4. The dry electrode film of claim 1, wherein the dryprelithiating material comprises about 0.5-10 wt. % of the dry electrodefilm.
 5. The dry electrode film of claim 1, wherein the dry activematerial is a dry cathode active material.
 6. The dry electrode film ofclaim 5, wherein the dry cathode active material comprises sulfur or amaterial comprising sulfur.
 7. An energy storage device comprising thedry electrode film of claim
 1. 8. The energy storage device of claim 7,wherein the energy storage device is a battery.
 9. A method offabricating a dry electrode film of an energy storage device,comprising: mixing a dry prelithiating material and a dry conductivecarbon additive to form a first dry mixture; mixing the first drymixture with a dry active material to form a second dry mixture; addinga dry fibrillizable binder to the second dry mixture to form a dryelectrode film mixture; and fibrillizing the dry binder in the dryelectrode film mixture.
 10. The method of claim 9, further comprisingcalendering the dry electrode film mixture to form a free-standing dryelectrode film.
 11. The method of claim 10, further comprising disposingthe free-standing dry electrode film over a current collector to form anelectrode.
 12. The method of claim 11, further comprising: incorporatingthe electrode into an energy storage device; and performing an initialcycling of the energy storage device, thereby oxidizing theprelithiating material.
 13. The method of claim 9, wherein mixing thefirst dry mixture with the dry active material further comprises mixinga dry carbon material and a dry conductive carbon material to form thesecond dry mixture.
 14. The method of claim 9, wherein mixing the dryprelithiating material and the dry conductive carbon additive isperformed so that the temperature of the first mixture is at most about150° C.
 15. The method of claim 9, wherein mixing the dry prelithiatingmaterial and the dry conductive carbon additive is performed so that thetemperature of the first mixture is at most about 100° C.
 16. The methodof claim 9, wherein mixing the dry prelithiating material and the dryconductive carbon additive results in electrical contact between primaryparticles of the prelithiating material and the conductive carbonadditive.
 17. The method of claim 9, wherein mixing the dryprelithiating material and the dry conductive carbon additive isperformed without excessive heating of the first dry mixture.
 18. Themethod of claim 9, wherein the ratio of the dry prelithiating materialand the dry conductive carbon additive is within a range of about 10:1to about 1:1.
 19. The method of claim 9, wherein the ratio of the dryprelithiating material and the dry conductive carbon additive is withina range of about 5:1 to about 5:3.
 20. The method of claim 9, whereinmixing the first dry mixture and the dry active material is performed sothat the temperature of the second mixture is at most about 100° C.